A plant in regular 5g black pastic pot should do well with 1g of water, dmama386. To determine when to water, insert a finger into the soil somewhat near the root ball to a depth of 4". If the soil feels almost dry or dry then water and mark it on the calendar. Do this for 1-2 weeks. Then review the information on the calendar and see how often you are watering. Then set the sprinkler or drip irrigation to water 1g on that same frequency (every 2,3,4,5,etc days). If the temperatures change around 10 degrees and stay there, use the finger method again. If your soil is sandy, add 50% more water than normal. If tomorrow's weather calls for wind advisories, consider watering the night before as windy days can cause hydrangeas to wilt.

Because your plant is new and is not established in your garden, it will have a tendency to wilt that will be more pronounced on years 1-2. When this happens, follow this approach...

If the wilting episode looks really bad, water immediately 1g of water. Otherwise, test the soil moisture with your finger. If it feels dry or almost dry then water 1g. Otherwise, wait until next morning and water 1/2g if still wilted. Most hydrangeas will recover on their own by night time.

Maintain 3-4 inches of mulch past the canopy at all times. This conserves soil moisture so you do not have to water often.

Hydrangeas usually do not need pruning provided your location allows them to grow to their full mature size. With mopheads, their mature size can be around 5-6' (HxW); I am assuming some of widest ones since you do not know the variety. After 3-4 years of growth, you may start getting a better feel.

Of course, for safety and aesthetic reason, you may need to prune sometimes. Since you do not know the variety, I recommend pruning after blooming (so you enjoy the blooms) and before the start of July. My shrubs in Texas begin to produce new flower buds in mid July so pruning by the end of June will make sure that you do not prune next year's flower buds. Further up north, bud production will start a little later.

Stems can be pruned about 1" from the brown whereas dried flower buds can be deaheaded.

Aluminum sulfate is used to change the color of the blooms to blue when your soil is alkaline. You need to determine if your soil is acidic or alkaline. To determine your soil pH, send a sample to the University of Florida Extension Soil Testing Laboratory (http://soilslab.ifas.ufl.edu ). An alternative is to ask neighbors who have hydrangeas, ask a plant nursery near your home or purchase a cheap soil pH measuring kit at a nursery, Lowe's, etc. If you have to add aluminum phosphate then follow the directions on the package for as long as you have the hydrangea. Then use the pH measuring kit to see how your soil is changing from alkaline to acidic. A kit that measures using the pH scale makes the process easier. Then again, growing the hydrangea in a pot instead would make this even easier to do, of course.

Hydrangeas do not require much fertilizer on normal soils. Sandy soils may require application of amendments (such as magnesium) and a soil test every 3-5 years is recommended. An application 1 cup of compost, manure or cottonseed meal in April-May and June should be enough but a soil test can tell you what else is needed. You can also add coffee grounds, liquid seaweed or liquid fish. Stop all fertilizers in July to help the plant go into dormancy after the fall. If your hydrangeas are like mine, they will go dormant between November-December. Use that time to remove plant debris.

Below is a website with lots of hydrangea information. Does that help you?

Luis

Here is a link that might be useful: More Hydrangea Information

Luis-Thanks so much for the great reply! Helps alot! Our neighbor has a huge hydrangea by their front door and it is lavender. The one I bought is lavender/pink and I would like for it to be really blue. My grandma had a really blue hydrangea that I just loved when I was a kid and I remember seeing it every summer. I would like this hydrangea to sort of be in memory of her :) Can I apply the aluminum sulfate right after planting or should I wait? If so, how long? Thanks!